| Icecast Installation and Management: A Guide to Open Source Audio Streaming | ||
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This chapter discusses the use of encoding tools that can transform raw or encoded audio into a compressed format such as MP3 or Ogg Vorbis. There are plenty of free encoding tools available for download and which fall under the GPL. Many of these are included by default with most Linux distributions. This chapter examines some of the more frequently used as well as more useful tools available. They can be used either in conjunction with other audio tools, or with icecast, or by themselves to re-encode audio.
One of the more popular encoders for transferring audio to MP3 format is LAME. LAME is a recursive acronym for LAME Ain't an MP3 Encoder. This is a definite play on other related terms such as GNU (GNU's Not Unix!) and the Scheme compiler called LIAR (Liar Imitates Apply Recursively). LAME is freely available from its home page at http://lame.sourceforge.net/. You may have to follow related links for older or more recent releases. The latest version works very well, both as a standalone product for encoding audio files into MP3 format or as a plugin for the icecast server.
LAME was originally designed as a patch against the dist10 ISO demonstration source and was originally incapable of generating an MP3 stream. Since then it has slowly replaced the ISO source until it became a new code set entirely. In May of 2000 when the last remnants of the ISO source code were removed, LAME was acknowledged as a fully LGPL'ed (Left GPL) MP3 encoder. The developers claim the speed and quality of this encoder exceeds all commercial competitors. Though early versions of icecast and its streamers worked well with the commercial releases, most developers now use LAME exclusively for their MP3 encoding needs.
LAME is billed as an educational tool and is intended for learning about MP3 encoding. That it can be used in production environments for streaming needs is just another facet of its use. It is the LAME project's goal to utilize open source to improve the acoustics, noise shaping, and speed of MP3 audio in general. LAME is distributed primarily in source code form and requires a C compiler. Binary releases are available with minimal searching. Enthusiasts distribute binary releases for many of the more popular Linux distributions. Beginning users are encouraged to initially use RPMs or related binary files and then quickly migrate to source code for compiling and installing purposes.
There are many programs that currently use or implement LAME within their releases. Some of those that will be discussed in this book are; DarkIce, LiveIce, and MuSE. There are many other programs designed for ripping audio CDs into MP3 format for Linux, Mac and the Windows platforms. Chances are if you have ever re-encoded an audio CD you used LAME in some form or another. An overview of the many programs implementing LAME at some level is found on the LAME URL: http://lame.sourceforge.net/links.html.
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